Surgical cutting accessory with an inlet port into which irrigating fluid is flowed

ABSTRACT

A surgical cutting accessory that includes inner and outer tubes. A cutting feature is attached to the inner tube. The proximal end of the inner tube is connected to an inner hub. The inner hub has features for engaging a drive shaft integral with a handpiece to which the accessory is attached. The outer hub has features that facilitate the removable coupling of the hub to the handpiece. The outer hub is formed with a bore through which the inner tube extends. The outer hub also has an inlet port that extends from an outer surface of the hub to the main bore. Irrigation fluid can be flowed through this port into the annular space between the inner and outer tubes. A seal is located adjacent the inlet port.

RELATIONSHIP TO EARLIER FILED APPLICATIONS

This Application is a divisional of U.S. patent application Ser. No.10/744,824 filed 23 Dec. 2003 now U.S. Pat. No. 7,717,931. applicationSer. No. 10/744,824 is a divisional of U.S. patent application Ser. No.09/302,148, filed 29 Apr. 1999, now U.S. Pat. No. 6,689,146. Thecontents of the priority applications are incorporated herein byreference.

FIELD OF THE INVENTION

This application relates generally to powered surgical handpieces suchas those employed in endoscopic surgery. More particularly, thisinvention is directed to a powered surgical handpiece that includes anirrigator for applying fluid to a surgical site, a suction conduit fordrawing fluid from the site, a means for clearing the suction conduitand a motor for actuating a complementary cutting accessory.

BACKGROUND OF THE INVENTION

The powered handpiece has evolved into an important tool for performingsurgical procedures. A typical powered handpiece includes a housing thatcontains an electrically driven motor. A coupling assembly is attachedto one end of the handpiece. The coupling assembly is used to releasablysecure a cutting accessory to the motor so that the motor, whenenergized, actuates the cutting attachment. The development of poweredsurgical handpieces and their complementary cutting accessories has madeit possible to cut, shape and remove both hard and soft body tissue atfaster rates and with a higher degree of accuracy than was possible withthe manually powered tools that preceded them.

When a cutting attachment is actuated, the cutting action causes loosetissue and other debris to develop at the surgical site. This materialis removed by applying an irrigation fluid to the site and also drawinga suction from the site. The irrigation fluid serves as a transportmedia for carrying the debris; the suction draws away the fluid and theentrained debris. In order to perform this irrigation and suction, somecutting attachments are provided with conduits through which fluid isapplied to and drawn from the surgical site. For example, cuttingattachments designed to perform endoscopic surgery or sinus surgeryoften include a static outer sleeve in which a rotating tube is fitted.The head of the rotating tube is provided with some type of cuttingsurface or cutting member. Each of these attachments is further shapedso that irrigation fluid can flow to the surgical site through theannular channel between the rotating tube and the static sleeve. Theinner rotating tube is further provided with an opening adjacent thehead through which a suction is drawn from the surgical site. Thus, theinner tube serves as the conduit through which the irrigation fluid anddebris are removed from the surgical site.

A powered handpiece intended for use with the above cutting attachmentsis designed with complementary features that facilitate the drawing ofthe suction away from the surgical site. Specifically, this type ofhandpiece is provided with a suction bore to which a suction pump isapplied. The coupling assembly allows fluid flow from the inside of therotating tube to the suction bore. Moreover, the handpiece is providedwith a valve for regulating fluid flow through the suction valve. Thus,a surgeon using this type of handpiece can, with one hand, bothmanipulate the cutting accessory and regulate the rate at which fluid isdrawn from the surgical site.

While current handpieces have provided useful for both driving cuttingattachments and drawing a suction, there are some disadvantagesassociated with their use. In particular, current handpieces and theircomplementary cutting attachments are designed so that irrigation fluidis introduced into the annular channel through a supply line that isseparate from the handpiece. While this supply line may be attached to ahandpiece, it has a free end that is typically located forward of thehandpiece coupling assembly. The free end of this line has to bemanually fitted to an inlet luer integral with the static sleeve. When,during a surgical procedure, the doctor wants to switch cuttingattachments, this line must first be removed from the cutting attachmentbeing separated from the handpiece. Then, after the new cuttingattachment is installed, the supply line must be manually fitted to thenew attachment. The time it takes to perform these steps adds to theoverall time it takes to perform the surgical procedure.

Moreover, in these surgical handpieces, the motor is in close physicalproximity to the path through which the suction fluid flows through thehandpiece. Accordingly, these handpieces must be constructed to includesufficient seals that prevent liquid flow into the components formingthe motor. However, over time, and owing to the presence of the movingparts against which these seals press, these seals can wear out.Consequently, it is not uncommon for fluid to enter the motor and causethe components forming the motor to corrode and/or malfunction. Once theintegrity of these seals diminishes, this corrosion and motor componentwear can occur at a relatively fast rate because the fluid drawn throughthe handpiece suction is saline.

Also, occasionally, debris can clog the cutting accessory rotating tubethrough which the suction is drawn from the surgical site. This cloggingis especially prone to occur in cutting accessories designed forperforming sinus surgery. This is because the diameter of the borethrough which this suction flow travels is relatively narrow. Presently,there are two ways a surgeon can try to remove this type of clog inorder to reestablish suction at the surgical site. One method involvesintroducing a large quantity of irrigation fluid into the surgical site.The surgeon takes this action by momentarily running the irrigation pumpused to supply fluid at a high speed/high flow flush setting. Theintroduction of this large quantity of water causes a large fluidpressure head to develop in the rotating tube upstream of the clog. Ifthe conditions are right, the pressure head of this fluid forces theclog-causing debris to flow downstream out of the rotating tube. Oneproblem with this clog removal technique is that the switches forregulating the irrigation pump are typically located off the handpiece.In order for the surgeon to be able to control the pump, he/she mustactuate a separate foot or hand switch or instruct an assistant toperform this operation. In each of these situations, the surgeon mayhave to significantly divert his/her attention from the actual surgicalprocedure being performed. Still another problem with this method ofclog removal is that, often, it simply does not work. Then, the surgeonis left with a situation in which excess fluid has been introduced intothe patient.

The second method of clog removal is more mechanical. This methodinvolves running a rigid wire down the rotating tube in order to forcethe clog out of the tube. When a surgeon has to take this action, he/shemust first withdraw the cutting attachment from the surgical site. Then,once the clog is removed, the cutting attachment must be repositioned sothat the surgical procedure can be completed. The need to perform thesetasks adds to the overall time it takes to perform the surgicalprocedure.

SUMMARY OF THE INVENTION

This invention relates to an improved powered surgical handpiece and acutting accessory for use with the handpiece. This invention includes amotor that has a rotor integral with the cutting accessory andcomplementary windings that are integral with the handpiece. Thehandpiece has a coupling assembly for holding the cutting attachment tothe handpiece that has a conduit through which irrigation fluid isintroduced into the attachment for application to the surgical site. Thehandpiece of this invention also has a valve for regulating fluid flowthrough the conduit through which a suction is normally drawn. Dependingon the setting of this valve, a suction can be drawn through the cuttingattachment, the suction shut off or irrigation fluid can be introducedinto the suction conduit in order to flush out any debris lodged in theconduit as

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is pointed out with particularity in the claims. The aboveand further features of this invention may be better understood byreference to the following description taken in conjunction with theaccompanying drawings in which:

FIG. 1 is a perspective view of a powered surgical handpiece of thisinvention and a complementary cutting accessory attached to thehandpiece;

FIG. 2 is a cross sectional view of the distal end of the handpiece aswell as of the portion of the cutting accessory seated in the handpiece;

FIG. 2A is a detailed cross sectional view of the motor depicted in FIG.2;

FIG. 3 is a perspective view of the cutting accessory;

FIG. 4 is a cross sectional view of the cutting accessory;

FIG. 5 is a enlarged view of the distal end of the handpiece;

FIG. 6 is a section view of a lateral slice of the handpiece taken alongline 6-6 of FIG. 5;

FIG. 7 is a cross sectional view of the inside of the handpiece;

FIG. 8 is a perspective cutaway view of the handpiece;

FIG. 9 is a section view of a lateral slice of the handpiece taken alongline 9-9 of FIG. 7;

FIG. 10 is a cross sectional view of the inside of the handpiecedepicting the fluid conduits in the end cap that lead to and from thevalve member;

FIG. 11 is a perspective view depicting the relationship of the slidelever, the slide rod and valve member;

FIG. 12 is a plan view of the relative position of the valve member andthe associated conduits with the valve member is in the suction full onstate;

FIG. 13 is a plan view of the relative position of the valve member andthe associated conduits when the valve member is in the suction partialon state;

FIG. 14 is a plan view of the relative position of the valve member andthe associated conduits when the valve member is in thesuction-and-purge off state;

FIG. 15 is a plan view of the relative position of the valve member andthe associated conduits when the valve member is in the purge flow onstate; and

FIG. 16 is a block diagram of how an alternative cutting accessory iscoupled to an alternative shaft of an alternative handpiece of thisinvention.

DETAILED DESCRIPTION

FIGS. 1 and 2 depict a powered surgical handpiece 20 of this inventionalong with a cutting accessory 22 that is driven by the handpiece. Thehandpiece 20 has a generally cylindrical sleeve-like shell 24 thatserves as the housing for the other components of the handpiece. Theproximal end of the cutting accessory 22 is also seated in shell 24.(Hereinafter “front”, “forward” and “distal” shall be understood tomeans portions of the handpiece 20 or cutting accessory 22 locatedtowards the end of the cutting accessory applied to the surgical site.“Rear”, “rearward” and “proximal” shall be understood to be portions ofthe handpiece 20 and cutting accessory 22 located away from the end ofthe cutting accessory applied to the surgical site.) Collectively, thehandpiece 20 and cutting accessory 22 are provided with components thatform a motor 26 for actuating the cutting accessory 22. The energizationsignals that are applied to the motor 26 are generated by a controlconsole 28 and applied to the motor over a power cable 30. One suchcontrol console 28 that can be employed to generate the energizationsignals is the TPS™ control console manufactured by the Applicant'sAssignee. A switch assembly, such as a foot switch, not illustrated andnot part of this invention, is used for regulating the actuation of thehandpiece motor 26. This switch assembly is connected to the controlconsole 28. Based on the signals generated by the switch assembly, thecontrol console 28 applies the energization signals to the handpiecemotor 26.

The handpiece 20 includes a coupling assembly 32 that releasably holdsthe cutting accessory 22 to the handpiece. An irrigation pump 34 appliesan irrigation fluid to a supply line 36 that is fitted in shell 24. Theirrigation fluid is introduced into the cutting accessory 22 forapplication to the surgical site through the coupling assembly 32. Inthe preferred version of the invention, irrigation pump 34 is a modulebuilt into and regulated by the control console 28.

A suction is drawn from the surgical site through the cutting accessory22 and handpiece 20 by a suction pump 38. A manually-set slide lever 40extends around the outside of the shell 24 and is located immediatelyrearward of the coupling assembly 32. Slide lever 40 sets the positionof a valve member 42 internal to the handpiece 20 which regulates fluidflow through a suction conduit integral with the cutting accessory 22.Depending on the position of the valve member 42, suction pump 38 maydraw a suction through the conduit, the suction flow may be attenuated,the suction flow may be completely shut off or the flow from irrigationpump 34 may be directed through the cutting accessory suction conduit.

The cutting accessory 22, now described by reference to FIGS. 3 and 4,includes a static hub 46 formed of plastic such as a polycarbonateplastic. Static hub 46 has a proximal end 48 with a circular crosssectional profile. The static hub 46 has a distal end 49 formedintegrally with the proximal end 48, that has a cross sectional profilethat is at least partially asymmetric relative to the longitudinal axisof the hub. In the depicted version of the invention, this static hubdistal end 49 is formed so that one surface thereof has a round profileand the opposed surface is shaped to define an alignment key 50. Thealignment key 50 projects beyond the circle defined by the proximal end48 of the hub 46 and is shaped to have a flat outer surface. A throughbore 47 extends axially through static hub 46 from the proximal end 48to the distal end 49.

The static hub 46 is further formed to have a rectangular notch 52 thatextends inwardly from the flat surface of the alignment key 50. Asdiscussed hereinafter, a complementary component of the handpiececoupling assembly 32 seats in notch 52 to hold the cutting accessory 22to the handpiece 20. A fluid inlet bore 54 extends perpendicularlyrelative to the longitudinal axis of accessory 22 from the alignment key50 to through bore 47. Fluid inlet bore 54 serves as the conduit throughwhich irrigation fluid is introduced into the cutting accessory 22 fromsupply line 36. In the depicted version of the invention, an irrigationseal 56 formed from a soft rubber such as is sold under the trademarkVITON by the duPont Company of Delaware is seated around the open end offluid inlet bore 54. Irrigation seal 56 is seated in a cutaway space 58integral with notch 52. Static hub 46 thus has a surface 59 that isinwardly stepped from the outer surface of the hub that defines the baseof space 58. Inlet bore 56 extends inwardly radially from surface 59into hub through bore 47. Seal 56 seats against surface 59. Seal 56 isshaped so that the outer surface thereof is flush with the outer flatsurface of the alignment key 50. Neither surface 59 nor space 58 extendcircumferentially around static hub 46. Therefore, it should beappreciated that seal 56 likewise does not extend circumferentiallyaround the static hub 46.

A rigid, outer tube 60 formed of stainless steel is firmly connected tothe static hub 46 and extends forward from the distal end of the throughbore 47. In the depicted version of the invention, the outer tube 60 isshown as having a closed distal end though that not may always be thecase. (The distal end of the outer tube 60 is the end of the tubeapplied to the surgical site.) Outer tube 60 is formed to have a fluidinlet opening 62 that is concentric with and has the same radius asfluid inlet bore 54.

Cutting accessory 22 also has a rotating hub 63 that is located rearwardof static hub 46. Rotating hub 63 is formed from a plastic such aspolycarbonate plastic. The rotating hub 63 has a main body 66 that islocated immediately rearward of proximal end 48 of static hub 46. In thedepicted version of the invention, the cross sectional profile ofrotating hub 63 is identical to that of the adjacent static hub proximalend 48.

The rotating hub 63 is formed to have a neck 68 and a head 70 thatextend forward from the main body 66 into the static hub proximal end48. More specifically, neck 68 extends forward from body 66 and has aconstant diameter cross section profile less than the diameter of themain body. Head 70 is shaped to have a tapered profile such that theportion of the head immediately adjacent neck 68 has a diameter greaterthan that of the neck and the most distal end of the head has across-section diameter approximately equal to the diameter of the neck.The neck 68 and head 70 are seated in complementary shaped bores 72 and74, respectively, formed in the static hub proximal end 48. Bores 72 and74, it will be observed, surround and are contiguous with through bore47. More specifically, the hubs 46 and hub 63 are formed so that thereis an interstitial gap between the outer surfaces of neck 68 and head 70and the inner surfaces of the static hub 46 that define bores 72 and 74.In preferred versions of the invention, this annular gap, notidentified, is between 20 and 25 mils (0.5 and 0.7 mm). This gap reducesfriction between the interface of the neck 68 and head 70 and the statichub 46.

Rotating hub 63 is further formed with an axially extending through bore76 that is concentric with the static hub through bore 47. An outwardlytapered counterbore 78 is formed with through bore 76 at the proximalend of the rotating hub 63.

A rotating inner tube 79 is securely mounted to the inner wall thatdefines through bore 76 in order to turn in unison with rotating hub 63.Inner tube 79 extends forward from the distal end of rotating hub 63into the center of outer tube 60. The distal end of inner tube 79 isformed to serve as a cutting head. In the depicted versions of theinvention, the distal end of the inner tube 79 is open and has sharpedges so that this end of the tube functions as a planar. It should, ofcourse, be recognized that different heads may be attached to the distalend of the inner tube so that the cutting accessory 22 may serve as aburr, a shaver, a resector or other cutting device.

It should be realized that when the cutting accessory 22 is a cutter ora shaver, the distal end of the static outer tube 60 is closed. In thesecutting accessories 22, the distal end of the inner tube 79 isdimensioned to abut against the inner wall of the closed distal end ofthe outer tube 60. Thus, the inner tube 79 holds the main body 66 andhead of the rotating hub 63 away from, respectively, the distal end ofthe static hub 46 and the inner wall of the static hub that defines bore74. This holding off of the rotating hub 63 from the adjacent surfacesof the static hub 46 as well as the fact that neck 68 is spaced inwardlyfrom the walls defining bore 72 serves to substantially eliminatefrictional between the hubs.

Outer and inner tubes 60 and 79, respectively, are further dimensionedso that there is a small annular channel 81 between the outer wall ofthe inner tube 79 and the adjacent inner wall of the outer tube 60.Annular channel 81 serves as the conduit through which irrigation fluidflows from the fluid inlet bore 54 and the fluid inlet opening 62 to thesurgical site. The hollow center of inner tube 79 serves as a conduit 82through which a suction is applied to the surgical site for drawingfluid and debris away from the site.

The handpiece 20 is now described in detail with an initial discussionof the construction of the coupling assembly 32, best seen by referenceto FIGS. 2, 5 and 6. The front end of the handpiece 20 is provided witha solid coupling body 86 formed of PEEK plastic that is seated in thefront end of shell 24. More specifically, in the depicted version of theinvention, the forward end of shell 24, is shaped to subtend an arc ofapproximately 200 to 260.degree. Immediately rearward of this section ofthe shell 24, the shell is shaped to have a forward-directed front plate83.

The section of coupling body 86 seated in shell 24 thus has an exposedouter surface 85. The coupling body 86 is further shaped to have a headsection 87 that extends forward of shell 24. Head section 87 has across-sectional profile that is approximately equal to that of theadjacent end of the shell 24 from which the head extends. Coupling body86 has an axially extending bore 88 dimensioned to receive static hub46. The coupling body 86 is formed so that bore 88 has a distal opening90 with a cross-sectional profile identical to that of the static hubdistal end 49, including the alignment key 50. This configurationinsures that the static hub 46 seats in coupling body 86 in a specificorientation for purposes to be explained below.

The coupling assembly 32 also includes an oval-shaped coupler arm 92.The arm 92 is slidably mounted to the outside of coupler body 86 so asto move perpendicularly relative to the longitudinal axis of thehandpiece 20. Coupler arm 92 has two parallel, spaced apart links 94each of which is seated in a separate slot 96 formed by an interstitialspace between the distal end of the shell 24 and the proximal end of thecoupler body head section 87. Links 94 are connected together at one endby a locking member 98. The locking member 98 is positioned adjacent anopening 102 in the exposed surface 85 of the coupler body 86 rearward ofhead section 87. Opening 102 extends into the distal section 90 of bore88. The locking member 98 is formed to have a tab 104 that extendsthrough opening 102 into bore 88. Tab 104 is the component of thecoupling assembly 32 that seats in notch 52 to hold the cuttingaccessory 22 to the handpiece 20. The tab 104 is formed with a forwardfacing surface 105 that is angled rearwardly to facilitate the fittingof the cutting accessory 22 to the handpiece 20.

Irrigation fluid is introduced into the cutting accessory 22 through thecoupler arm 92. Specifically, the distal end of the supply line, distalsupply line 36 a in the drawings, is fitted into a rearward facing bore106 formed in locking member 98. Locking member 98 has a cylindricaloutlet fitting 108 that is in fluid communication with bore 106 and isdirected inwardly towards the longitudinal axis of the handpiece 20.Outlet fitting 108, which is located rearward of tab 104, is positionedso that when the tab 104 seats in the cutting accessory notch 52, thefitting 108 seats in the opening integral with irrigation seal 56. Thus,when the cutting accessory 22 is mounted to the handpiece 20, fluidflows from the supply lines 36 and 36 a, through bore 106 and fitting108, into accessory inlet bore 54, inlet opening 62 and channel 81 tothe surgical site.

The ends of links 94 distal from locking member 98 are connectedtogether by a semi-circular web 110. Two springs 112 bias coupler arm 92so that tab 104 is normally urged into bore 88. The springs 112, whichare parallel to each other, are connected at one end to separate posts114 fitted in coupler body head section 87. The opposed end of eachspring 112 is connected to a small set screw 116 that extends forwardfrom an adjacent one of the links 94. The coupler body head section 87is further formed to have opposed grooves 118 in which each spring 112is seated. Since the springs 112 are seated in grooves 118, thelikelihood of an individual inadvertently disturbing a spring or fingeror an article of clothing becoming caught in one of the springs issubstantially eliminated.

The motor 26 seen best in FIGS. 2 and 2A, includes a stator 122 that ismounted in the shell 24 and a set of magnets 124 that are disposed inthe cutting accessory rotating hub 63 as seen in FIGS. 2, 4 and 7. Inone preferred version of the invention, the motor is a four-pole,three-phase brushless, sensorless DC motor. More specifically, thestator 122 includes a set of three windings 121 that are wound around acage 123. Electrically, the windings are 120.degree. apart from eachother. It should be understood that physically, the windings mayoverlap. The stator 122 is encased in an insulating shell 125 that isformed from non-conductive material such as PEEK plastic. Shell 125 isshaped so as to define an axially extending center space 126 in whichthe cutting accessory rotating hub 63 is seated. More particularly, theshell 125 is dimensioned so that there is a small air gap between theinner wall of the shell defining space 126 and the outer wall of therotating hub 63. This air gap is approximately 20 mils, (0.5 mm). Thisair gap essentially eliminates the rotating friction between therotating hub 63 and the shell 125.

The rear end of stator shell 125 is seated on an annular step 128 formedintegrally with handpiece shell 24. Step 128 extends inwardly from theinner wall of handpiece shell 24 towards the longitudinal center of thehandpiece 20.

Since motor 26 is a four-pole motor, four magnets 124 are mounted in therotating hub. The magnets 124 are elongated members that are spacedequiangularly around the longitudinal axis of the cutting accessory 22.The magnets are formed so that their N/S polar orientation is locatedalong an axis perpendicular to the longitudinal axis of the cuttingaccessory 22. Thus, for a first one of the magnets 124, the North poleis oriented towards the center of the rotating hub. The magnets 124adjacent the first magnet are arranged so that their South poles areoriented towards the center of the rotating hub.

The magnets 124 may have a cross sectional profile that is either curvedor squared. Alternatively, the magnets may even have arcuate crosssectional profile. In these versions of the magnets 124, the outer faceof each magnet may have a convex profile having a first radius while theinner face of the magnet has a concave profile with a radius less thanthat of the first radius. The magnets 124 may be made out of anyappropriate material such as samarium cobalt.

A plunger 134 is seated in the rearward portion of stator 122. Theplunger 134 is formed from stainless steel. The plunger 134 has acylindrical stem 136. Stem 136 is mounted in a plunger bearing assembly138. The plunger bearing assembly 138 is seated in the front end of thevalve member 42 as will be described hereinafter. Plunger 134 is furtherformed with a head 140 that is formed integrally with and has a largercross sectional diameter than the stem 136. In the depicted version ofthe invention, plunger head 140 is dimensioned so that it comes closeto, but does not abut the adjacent inner wall of the stator 122. Theplunger head 140 has a center section 142 that extends forward from theouter perimeter of the head. The center section 142 of the plunger head140 seats in counterbore 78 formed in the proximal end of rotating hub63.

A bore 146 extends axially through plunger 134 from the proximal end ofthe plunger to the distal end. Bore 146 serves as a conduit throughwhich fluid flows between valve member 42 and rotating hub bore 76. Inthe depicted version of the invention, the plunger head 140 has acounterbore 148, concentric with bore 146, that has the same diameter asthe rotating hub bore 76.

A coil spring 150 is disposed around plunger stem 136 and extendsbetween plunger bearing 138 and the rearward facing surface of plungerhead 140. Spring 150 provides the biasing force that urges the plunger134 forward so that the plunger imparts a like force to cuttingaccessory 22. A retaining ring 152 fitted in a groove extending aroundthe end of stem 136 seated within the valve member 42 (groove notidentified). Retaining ring 152 abuts against the rearward facingsurface of plunger bearing assembly 138 to prevent the plunger 134 fromseparating from the bearing assembly 138.

An explanation of how fluid is selectively introduced into and drawnfrom conduit 82 of cutting accessory 22 through the handpiece 20 of thisinvention is now set forth with initial reference to FIGS. 7-9. As seenin these drawings, a solid, cylindrical end cap 156 formed of PEEKplastic is seated in the proximal end of shell 24. End cap 156 is formedwith a suction bore 158 that extends laterally through the end cap. Itwill be observed that suction bore 158 is laterally offset from thelongitudinal axis of the end cap 156. Suction bore 158 is formed to havea threaded counterbore 160 which is located at the proximal end of theend cap 156. A luer fitting 162 is seated in suction bore counterbore160. The luer fitting 162 serves as a means to connect a suction line164 between the suction bore 158 and suction pump 38. The opposed end ofsuction bore 158 defines an opening 165 in the distal end face of endcap 156.

End cap 156 is also formed to have a supplemental conduit 166. Thesupplemental conduit 166 serves as the conduit in which the electricalconductors integral with the handpiece 20 are seated (conductors notillustrated). The supplemental conduit 166 extends forward from theproximal end of the end cap 156. In the depicted version of theinvention, end cap 156 is formed so that supplemental conduit 166 islaterally offset from the longitudinal axis of the handpiece 20.Supplemental conduit 166 has two sections. There is a proximal section168 in which the conduit is essentially parallel to the suction 158.There is also a distal section 170 that is contiguous with and extendsforward from proximal section 168. Distal section 170 angles away fromproximal section 168 and opens in the side of the end cap 156 at a pointrearward of the distal end of the end cap. The conductors extend out ofthe end of the opening of supplemental conduit distal section 170 andseat in a groove 171 formed on the inner wall of shell 24

(FIG. 9). The conductors extend from the shell 24 to the stator 122 toprovide energization signals to motor 26. A tube-shaped ferule 169extends rearwardly from the open proximal end of the supplementalconduit 166. Ferule 169 protects the end of the cable 30 that extendsinto the conduit 166.

The irrigation fluid supply line 36 is fitted in a groove 172 thatextends longitudinally along the outside of shell 24 seen best byreference to FIGS. 2, 5 and 10. Supply line 36 terminates at one end ofa T-connector 174 mounted to the end cap. Distal supply line 36 aextends from the opposed end of T-connector 174 into the bore 106associated with coupler arm 92. More specifically, groove 172 extendsforward a short distance from T-connector 174 and distal supply line 36a is seated in the groove. Distal supply line 36 a extends throughgroove 172 and out through an opening 175 in the shell front plate 83.The forward end of the distal supply line 36 a is the end of the linefitted to coupling arm bore 106.

Focusing on FIG. 10, it can be seen that the center stem of T-connector174 is mounted in an L-shaped irrigation bore 176 formed in the distalend of end cap 156. Bore 176 has an opening 178 in the distal end faceof the end cap 156.

Valve member 42, now described by reference to FIGS. 7 and 11, is shapedto have a generally cylindrical shape. The valve member 42 has acircular, disc-like base 180 that abuts the distal end face of end cap156. The space forward of end cap 156 is the valve chamber 179 ofhandpiece 20. Valve member base 180 has a tear-dropped shaped opening182 that, depending on the position of the valve member 42, isselectively positioned to be in registration with suction bore opening165 or irrigation bore opening 178. The valve member 42 is furtherformed to have tube-like body 184 that extends forward from the distalend of base 180. The body 184 is the portion of the valve member 42 towhich plunger bearing assembly 138 is mated and in which the plungerstem 136 extends. More specifically, the inner wall of valve member body184 is formed to define an annular step 186 in which the plunger bearingassembly 138 is seated.

The setting of valve member 42 is controlled by slide lever 40. Theslide lever 40 has a curved section 190 that fits around the portion ofshell 24 that surrounds coupler body 86. Slide lever 40 also has a flatsection 192 integral with the curved section 190 that is located againstthe exposed surface 85 of the coupler body below coupler arm 92. A sliderod 194 extends rearwardly from slide lever flat section 192. Slide rod194 is seated in a longitudinally extending groove 196 formed on theinside wall of shell 24. In order to ensure that the slide rod seats ingroove 196, the rod is formed to have a semi-circular cross sectionalprofile.

Slide rod 194 is provided with a pin 198 (shown in phantom) that extendsinwardly towards the longitudinal axis of the handpiece 20. Pin 198seats in a helical groove 202 (shown in phantom) formed in the outersurface of valve member body 184. Thus, the forward/rearwarddisplacement of slide lever 40 and slide rod 194 controls the rotationalposition of valve member 42.

An extension rod 204, seen in FIGS. 8 and 9, is attached to the proximalend of slide rod 194 to move with the slide rod. Extension rod 204 has agenerally circular cross sectional profile. The outer half of extensionrod 204 seats in shell groove 196. The inner half of extension rod 204seats in a groove 206 formed along the outer wall of end cap 156. Asmall magnet 208 is mounted in an opening in extension rod locatedadjacent the distal end of the rod 204 (opening not identified).

Extension rod 204 is shaped to have a reduced diameter pin 210 thatextends rearwardly from the proximal end of the rod 204. Pin 210 seatsin a forward-facing bore 220 (shown in phantom) formed in the proximalend of end cap 156. A spring 212 extends around pin 210. Spring 212provides a biasing force that push extension rod 204, slide rod 194 andslide valve 40 forward. Thus, slide valve 40 is normally positioned tobe located immediately rearward of locking member 98.

A reed switch 216, or other sensor, is seated in the end cap 156 tomonitor the displacement of magnet 208. In the depicted version of theinvention, reed switch 216 is mounted in a branch channel 218 thatextends laterally away from the proximal section 168 of supplementalconduit 166. The signal across the reed switch is monitored by a circuitinternal to control console 28. The electrical conductors (notillustrated) that extend to reed switch 216 are fitted in conduit 166.Also, in the depicted version of the invention, branch channel extendsto groove 206 though this need not always be the case. The open/closedstate of reed switch 216 is monitored by a controller internal toirrigation pump 34.

A tube-like handgrip 220 formed of rubber surrounds shell 24. Thehandgrip 220 surrounds the portion of the shell that extends rearwardfrom plate 83.

The handpiece 20 of this invention is readied for use by the fitting ofthe cutting accessory 22 to the handpiece. This is performed byinserting the accessory hubs 46 and 63 into the open end of handpiecebore 88. When the static hub alignment key 50 seats in the bore distalopening 90, the flat face of the key abuts against the angled forwardfacing surface 105 of tab 104. Owing to the angle of surface 105, thisaction causes the tab 104 to automatically retract away from bore 88 sothat the cutting accessory 22 can continue to be fitted in place. Oncenotch 52 of static hub 46 comes in registration with tab 104, springs112 urge locking member 98 towards the center axis of the handpiece sothat the tab seats in the notch. The seating of the tab 104 in notch 52locks the cutting accessory 22 in place.

Simultaneously with the seating of tab 104 in notch 52, outlet fitting108 comes into registration with accessory inlet bore 54. Thus, thelocking of the cutting accessory 22 to the handpiece 20 of thisinvention results in the automatic establishment of a path through whichirrigation fluid can flow through supply lines 36 and 36 a into theannular channel 81 of cutting accessory 22. Thus, once the couplingaccessory 22 is fitted to the handpiece 20 additional time need not bespent establishing this fluid connection.

It should also be understood that when irrigation fluid is introducedinto the inlet bore 54, the fluid does not flow rearward beyond theinterface of the static hub 46 and rotating hub 63. This is because thepressure head of the fluid is not sufficient to force the fluid betweenthe narrow gap between the hubs 46 and 63.

When it is necessary to remove the cutting accessory 22 from thehandpiece 20, all one needs to do is manually urge coupler arm web 110inwardly towards shell 24. This action causes tab 104 to retract awayfrom cutting accessory notch 52. Simultaneously with the retraction oftab 104, outlet fitting 108 retracts away from bore 54. Once the tab 104is moved away from notch 52, cutting accessory 22 can be manuallyremoved from bore 88. The removal of the cutting accessory 22 isfacilitated by the fact that, once the tab 104 is so retracted, theforce of the plunger spring 150 is fully released. Thus, the spring 150pushes the plunger 136 forward so the plunger causes a like displacementof the cutting accessory 22 out of the forward end of the handpiece 20.

The cutting accessory 22 is actuated by selectively applyingenergization currents to the windings integral with the stator 122.These currents cause magnetic fields to develop which attract themagnets 124 internal to rotation hub 63. The attraction of the magnets124 to the windings causes rotation of hub 63 as well as inner tube 79integrally attached thereto. Plunger 134, which is pressed againstrotating hub 63, rotates with the hub. An advantage of this arrangementis that in this construction only the single bearing assembly 138 isrequired to insure the free rotation of rotor that is integral with themotor. Moreover, since the windings and magnets 124 are contained intheir own sealed housings, and there are no bearings, it is notnecessary to provide a separate sealed housing for the motor 26. Twoadvantages of this construction are that it eliminates both the cost andweight of having to provide a sealed housing. Still another benefit ofthis feature of the invention is that the motor 26 of this handpiece 20does not have any metal components that are exposed to fluid in theevent a seal wears or breaks. Thus, there is little likelihood that themotor of this invention will malfunction due to corrosion-inducedcomponent failure.

The handpiece 20 of this invention is further configured to regulatewhether or not a suction is drawn through or irrigation fluid is appliedto conduit 82 integral with the cutting accessory inner tube 79. Duringnormal operation of the handpiece 20, valve member 42 has the rotationalorientation depicted in FIG. 12. Here, the valve member 42 is positionedso that the largest diameter section of base opening 182 is inregistration with opening 165 integral with suction bore 158. Thus, whenthe valve member 42 is in this position, the maximum possible suction isdrawn from the surgical site through inner tube conduit 82, rotating hubbore 76, plunger bore 146 and the suction bore by suction pump 38.Further, when the valve member 42 is in this position, base 180 coversand closes irrigation bore opening 178. The sealing closed of opening178 prevents irrigation fluid from being introduced into the center ofthe valve member when the suction is being drawn.

A surgeon attenuates the suction drawn at the surgical site by movingslide lever 40 rearward towards handgrip 220. This motion causes a likedisplacement of slide rod 194. The displacement of slide rod 194 causesvalve member 42 to rotate first to the position depicted in FIG. 13.When the valve member 42 is in this position, the narrow diametersection of valve member base opening 182 is in registration with suctionbore opening 165. Thus, at this time, a reduced volume suction flow isdrawn by the pump 38 from the surgical site through the inner tubeconduit 82 and the valve member 42.

The surgeon may totally turn off the suction drawn at the surgical siteby simply moving the slide lever 40 rearwardly. The like movement thisinduces in the slide rod 194 and pin 198 causes the pin to rotate thevalve member 42 into the position shown in FIG. 14. When in this state,the valve member 42 covers the both suction bore opening 165 and theirrigation bore opening 178. Thus, at this time, there is no fluid flowin any direction through the inner tube conduit 82 to or from thesurgical site.

The handpiece 20 of this invention is configured to direct a purge flowthrough the inner tube conduit 82 in the event the conduit becomesclogged. Specifically, if this event occurs, or for another reason thesurgeon wants a very large fluid flow to be introduced into the surgicalsite, the surgeon presses the slide lever 40 so that the lever is in itsmost rearward position. This displacement of the slide lever 40 and theassociated slide rod 194 results in two effects. First, thisdisplacement causes the valve member 42 to rotate into the positiondepicted in FIG. 15 in which the large diameter portion of base opening182 comes into registration with irrigation bore opening 178. Secondly,the magnet 208 that moves with the slide rod 194 moves very close toreed switch 216. This motion causes the reed switch 216 to close so thatthe signal produced by the switch changes state. This signal change isinterpreted by control console 28 as an instruction to boost the rate atwhich fluid is discharged from the irrigation pump 34. Thus, the movingof the slide valve 40 to the purge position resets the valve member 42so that irrigation fluid is directed through inner tube conduit 82 andsets the irrigation pump 34 to force a relatively high pressure flowthrough this conduit. Collectively, this means that when the handpiece20 is in the purge state, a relatively high pressure stream of fluid isdirected through the inner tube conduit 82 towards the surgical site. Inmany situations, this high pressure fluid stream has enough force todislodge the debris that are blocking normal suction flow through theinner tube 79.

Thus, the handpiece 20 of this invention provides a means forautomatically establishing and breaking an irrigation connection to thecutting accessory 22, has relatively few moving parts and has means toprovide a purge flow to the conduit integral with the cutting accessorythrough which the suction flow is normally drawn.

It should be understood that the foregoing description is directed toone specific embodiment of the invention. It will be apparent, however,from the description that alternative constructions of the invention arepossible. For example, not all versions of the invention may have anoutlet fitting for providing a fluid communications path to thecomplementary cutting accessory. Similarly, other versions of thehandpiece may not be constructed so that the rotating hub of the cuttingaccessory forms part of the motor or with a valve member that can beused to introduce a purge flow into the suction conduit integral withthe cutting accessory.

For example, it may be desirable to provide a handpiece andcomplementary cutting attachment of this invention with just thedescribed motor 26. These particular components would thus be designedas tools for conventional surgery in which the handpiece does not alsoprovide irrigation fluid and/or draw suction from the site. Similarly,it may be desirable to provide a handpiece that simply functions as anconduit for supplying irrigation fluid to and/or drawing a suction fromthe surgical site that has the features of this invention. Specifically,it will be noted that the setting of valve 42 does not effect the alwaysopen fluid connection between supply lines 36 and 36 a. So when valve 42is in the purge position, there is also fluid flow to the surgical sitethrough annual channel 81.

Also, the components from which the handpiece and complementary cuttingaccessory are formed may have alternative constructions than what hasbeen described. For example, it may be desirable to design the couplingassembly with multiple fingers that are positioned to move towards andaway from the cutting accessory. In this version of the invention, thecutting accessory would be formed with recesses in which these fingersseat. The seating of the fingers in these recesses holds the cuttingaccessory to the handpiece. In these versions of the invention, theinlet fitting may be built into one of the fingers.

It should also be recognized that some versions of the invention, thedistal end of the outer tube 60 of the cutting accessory 22 may be openended. This may be the case when the inner tube 79 is provided with aburr at its head end. In these versions of the invention, the tubescannot be configured to hold the rotating hub 63 off away from thestatic hub 46. Accordingly, in these versions of the invention, a flatring formed of a low friction plastic such as the plastic sold under thetrademark TEFLON by the duPont Company, may be fitted around the forwardend of the rotating tube main body 66. This ring serves as a bearing tominimize the friction between the rotating hub 63 and the static hub 46.

Alternatively, in some versions of the invention, the distal end of theinlet fitting 108 may seat in a counter bore formed integral with fluidinlet bore 54. An advantage of this version of the invention is that itmay eliminate the need to provide the irrigation seal 56 around bore 54.

Also, alternative versions of the motor may be provided. For example,while not optimal, the stator may be embedded in the rotating hub 63 andthe magnets may be mounted to the handpiece. In these versions of theinvention, some type of brushes integral with the handpiece wouldprovide an electrical path between the control console 28 and thewindings integral with the stator. Also, in some versions of theinvention Hall sensors may be mounted in the handpiece 20. These sensorswould provide signals that indicate the rotational position of therotating hub magnets 124. The control console 28, in turn, uses thesignals representative of the position of these magnets as an input forregulating the energization of the stator windings.

Moreover, it should likewise be understood that the rotating hub 63 maybe provided with more or less magnets 124 than has been described.Typically, the rotating hub 63 will be provided with an even number ofmagnets. Similarly, stator 122 may have other constructions than whathas been described.

It should likewise be appreciated that there may be versions of theinvention in which no part of the motor is built into the cuttingaccessory 22. In these versions of the invention, as seen in FIG. 16,the rotating hub 63 a may be provided with notches 213 or other meansfor engaging a complementary coupling member 214 that is integral withthe shaft 216 of the motor 218 built into the handpiece 20 a. In theseversions of the invention, once the rotating hub engages with the shaft,the hub, as well as inner tube 79 rotate in unison with the shaft.

Also, it should be clear that the structure of the valve member may veryfrom what has been described. Clearly, the valve member can rotate alongan axis different than the longitudinal axis that runs through thehandpiece 20. It should be clear that, in these versions of theinvention the conduits in the end cap 156 will have differentorientations than what has been described. Furthermore, there is norequirement that in all versions of the invention in which the handpiece20 is capable of directing a purge flow through the suction conduit ofthe cutting accessory 22 that the handpiece also have a switch assemblyfor controlling the rate of the purge flow. Similarly, in other versionsof the invention, by appropriately designing the components, it may bepossible to provide one of two purge flows to the suction conduit; afirst low-pressure flow and a second high-pressure flow. Thisarrangement may be possible by constructing the handpiece so that onlyafter irrigation bore opening 178 is placed in full registration withthe valve member opening 182 does the reed switch, upon furtheractuation of the slide lever 40, close.

Moreover, in other versions of the invention, a switch assembly forregulating the energization of the suction pump 38 may be built into thehandpiece. This switch assembly may include a second reed switch that isactuated by magnet 208 or a second magnet that is displaced by theactuation of slide lever 40. Depending on the open/closed state of thisreed switch, the control console 28 may either increase or decrease thesuction drawn by pump 38.

Therefore, it is an object of the appended claims to cover all suchmodifications as come within the true spirit and scope of thisinvention.

What is claimed is:
 1. A surgical cutting accessory for attachment to asurgical handpiece, the surgical handpiece having an open-ended bore anda discharge port that opens into the bore, said cutting accessoryincluding: a static hub, said static hub shaped to have: a sectiondimensioned to be seated in the surgical handpiece bore; an outersurface; a stepped surface that is located in the section of said outerhub dimensioned to be seated in the surgical handpiece bore and that islocated inwardly of the adjacent hub outer surface; axially opposedfirst and second ends; a through bore that extends from the first end tothe second end; a geometric feature for receiving a locking element thatholds said static hub to the handpiece; and an inlet bore for receivingfluid from the handpiece discharge port, said inlet bore extendinginwardly from an opening in the stepped surface of said static hub tothe through bore; a seal formed from compressible material mounted tothe static hub adjacent the static hub stepped surface, said seal havean exposed surface located adjacent and outwardly of the opening intothe static hub inlet bore; an outer tube mounted to said static hub thatextends outwardly from the second end of said static hub over thethrough bore of said static hub; a rotating hub that is located adjacentthe first end of said static hub, said rotating hub having: featuresconfigured to cooperate with the handpiece so that actuation thehandpiece results in rotation of said rotating hub; and a bore with adistal end; and an inner tube having: a proximal section that isattached to said rotating hub so that said inner tube rotates in unisonwith said rotating hub; a center bore that opens into the distal end ofthe rotating hub bore through which a suction can be drawn; and a distalend spaced from the proximal end, said inner tube positioned to extendforward of said rotating hub through the through bore of said static huband into said outer tube wherein, said inner tube and said outer tubeare spaced apart from each other so as to form an annular channeltherebetween, the inlet bore of said static hub being in fluidcommunication with the annular channel and wherein, the distal end ofsaid inner tube is provided with a cutting head.
 2. The cuttingaccessory of claim 1, wherein said outer hub and said seal arecollectively shaped so that the exposed face of said seal is flush withthe outer surface of the static hub dimensioned to be seated in thesurgical handpiece bore.
 3. The cutting accessory of claim 1, whereinsaid static hub is formed to have an asymmetric cross sectional profile.4. The cutting accessory of claim 1, wherein said seal is seated on thestatic hub stepped surface.
 5. The cutting accessory of claim 1, whereinsaid static hub is formed so that the stepped surface from which theinlet bore extends does not extend circumferentially around said statichub.
 6. The cutting accessory of claim 1, wherein said seal is formedwith a though bore that opens into the opening into the static hub inletbore.
 7. The cutting accessory of claim 1, wherein said seal has a firstsection located between the opening into the static hub inlet bore andthe first end of the static hub and a second section located between theopening into the static hub inlet bore and the second end of the statichub.
 8. The cutting accessory of claim 1, wherein said rotating hubfeatures for cooperating with the handpiece are features for engaging amotor driven rotating shaft that is part of the handpiece so that therotation of the shaft results in the rotation of said rotating hub andsaid inner tube.
 9. The cutting accessory of claim 1, wherein thegeometric feature in said static hub for receiving the handpiecefastening member includes a notch located forward of the inlet bore andrearward of the static hub distal end.
 10. The cutting accessory ofclaim 1, wherein the static hub stepped surface has a section thatextends proximally from the static hub inlet bore opening and a sectionthat extends distally from the static hub inlet bore opening.
 11. Acutting accessory for use with a surgical handpiece that has a bore forreceiving said accessory and an outlet port that opens into the borethrough which irrigation fluid can be discharged, said cutting accessoryincluding: an inner hub, said inner hub having: opposed proximal anddistal ends; geometric features for engaging a rotating shaft internalto the handpiece so that the rotation of the shaft results in rotationof said inner hub; a bore that is open to the distal end of said hub; aninner tube having a hollow center that opens into the bore of said innerhub through which a suction can be drawn; said inner tube secured tosaid inner hub to extend forward from the distal end of the inner hub,said inner tube having a distal end spaced from said inner hub to whicha cutting head is mounted; an outer hub disposed over said inner tubeand located adjacent said inner hub so as to extend forward of thedistal end of said inner hub, said outer hub having: at least a sectiondimensioned to seat in the surgical handpiece bore; an outer surface;opposed proximal and distal ends; a recessed surface located inwardly ofthe outer surface within the section of said outer hub dimensioned toseat in the surgical handpiece bore; a through bore that extends betweenthe ends through which said inner tube extends; an inlet bore that iscontiguous with and extends outwardly from the through bore, the inletbore having an opening in the recessed surface for receiving irrigationfluid discharged from the handpiece outlet port; and a geometric featurethat engages with a complementary fastening element of the surgicalhandpiece that holds the outer hub in the handpiece bore; a seal formedfrom compressible material mounted to the outer hub and positionedadjacent the opening into the outer hub inlet bore, said seal positionedto extend above the outer hub inlet bore and above the outer hubrecessed surface so that, when the outer hub is seated in the handpiecebore, the seal abuts the portion of the handpiece that defines thehousing outlet port; and an outer tube that extends from said outer hubthat at least partially extends over said inner tube, said inner tubeand said outer tube defining a channel therebetween through whichirrigation fluid introduced through the outer hub inlet bore into theouter hub through bore flows.
 12. The cutting accessory of claim 11,wherein said outer hub and seal are collectively shaped so that saidseal has an outer face that is flush with an adjacent section of theouter surface of said outer hub.
 13. The cutting accessory of claim 11,wherein: said outer hub is shaped so that the recessed surface fromwhich the outer hub inlet bore opens extends circumferentially aroundthe inlet bore opening; and said seal is formed with an opening thatopens to the outer hub inlet bore.
 14. The cutting accessory of claim11, wherein said outer hub is formed so that the recessed surface doesnot extend circumferentially around said outer hub.
 15. The cuttingaccessory of claim 11, wherein said seal is formed from a single blockof material.
 16. The cutting accessory of claim 11, wherein, said sealincludes: a proximal section located between the opening into the outerhub inlet bore and the outer hub proximal end; and a distal sectionlocated between the opening into the outer hub inlet bore and the outerhub distal end.
 17. The cutting accessory of claim 11, wherein thegeometric feature in said outer hub for receiving the handpiecefastening member includes a notch located forward of the inlet bore andrearward of the outer hub distal end.
 18. A cutting accessory for usewith a surgical handpiece that has a bore for receiving said accessoryand an outlet port that opens into the bore through which irrigationfluid can be discharged, said cutting accessory including: an outer hub,said outer hub shaped to have: a portion shaped to fit in the handpiecebore; opposed proximal and distal ends; a through bore that extendsthrough said hub between the ends; an outer surface; a stepped surfacein the portion of said hub shaped to fit in the handpiece bore that islocated inwardly of the outer surface; and a inlet bore that has aninlet opening in the stepped surface, the inlet bore extending inwardthrough said outer hub so as to open into the hub through bore; a sealmounted to said outer hub, said seal formed from compressible materialand having a proximal section located adjacent the outer hub outersurface between the inlet bore inlet opening and the outer hub proximalend and a distal section located between the inlet bore inlet openingand the outer hub distal end, wherein both sections of said seal extendabove the hub stepped surface and the inlet bore inlet opening; an innerhub, said inner hub having: geometric features for engaging a rotatingshaft internal to the handpiece so that the rotation of the shaftresults in rotation of said inner hub; and a distal end with a bore thatextends proximally therefrom and said inner hub is positioned to extendaway from the proximal end of the outer hub; an inner tube connected tosaid inner hub that extends forward from the distal end of said innerhub, through the outer hub through bore and distally forward of saidouter hub, said inner tube having a conduit that opens into the innerhub bore and a distal end spaced from said outer hub to which a cuttinghead is mounted; and an outer tube that extends from said outer hub thatat least partially extends over said inner tube, said inner tube andsaid outer tube defining a channel therebetween through which irrigationfluid introduced through the outer hub inlet bore into the outer hubmain bore flows.
 19. The cutting accessory of claim 18, wherein saidseal is seated on the outer hub stepped surface.
 20. The cuttingaccessory of claim 18, wherein said seal is formed from a single blockof material.
 21. The cutting accessory of claim 18, wherein the innerhub features for engaging the handpiece rotating shaft are notches. 22.The cutting accessory of claim 18, wherein the geometric feature in saidouter hub for receiving the handpiece fastening member includes a notchlocated forward of the inlet bore and rearward of the outer hub distalend.
 23. The cutting accessory of claim 18, wherein said outer hub isformed so that the stepped surface does not extend circumferentiallyaround said outer hub.
 24. The cutting accessory of claim 18, whereinthe outer hub stepped surface has a section that extends proximally fromthe outer hub inlet bore opening and a section that extends distallyfrom the outer hub inlet bore opening.